A lot of these pictures changed photography, that is true. But without "Napalm Girl" or "Birmingham Dogs" you can't have a serious list of "photographs that changed the world". "Napalm Girl" was a tipping point in support for the Vietnam War.

"Vietnamese photographer Nick Ut describes the day in June 1972 when he photographed a nine-year-old girl, Kim Phuc, fleeing her village after a napalm attack - a picture that won him a Pulitzer prize." -BBC News
http://news.bbc.co.uk/2/hi/asia-pacific/4517597.stm

Birmingham Dogs:
http://www.rethinkingschools.org/img/archive/20_02/RS_20_02_51.jpg